(Footnote.  It has been attempted, and with much ingenious reasoning, by Mr. Semeyns in the third volume of the Haerlem Transactions which have but lately fallen into my hands.)

Land and sea breezes.

Thus much is sufficient with regard to the periodical winds.  I shall proceed to give an account of those distinguished by the appellation of land and sea breezes, which require from me a minuter investigation, both because, as being more local, they more especially belong to my subject, and that their nature has hitherto been less particularly treated of by naturalists.

In this island, as well as all other countries between the tropics of any considerable extent, the wind uniformly blows from the sea to the land for a certain number of hours in the four and twenty, and then changes and blows for about as many from the land to the sea; excepting only when the monsoon rages with remarkable violence, and even at such time the wind rarely fails to incline a few points, in compliance with the efforts of the subordinate clause, which has not power, under these circumstances, to produce an entire change.  On the west coast of Sumatra the sea-breeze usually sets in, after an hour or two of calm, about ten in the forenoon, and continues till near six in the evening.  About seven the land-breeze comes off, and prevails through the night till towards eight in the morning, when it gradually dies away.

Cause of the land and sea-breezes.

These depend upon the same general principle that causes and regulates all other wind.  Heat acting upon air rarefies it, by which it becomes specifically lighter, and mounts upward.  The denser parts of the atmosphere which surround that so rarefied, rush into the vacuity from their superior weight; endeavouring, as the laws of gravity require, to restore the equilibrium.  Thus in the round buildings where the manufactory of glass is carried on, the heat of the furnace in the centre being intense, a violent current of air may be perceived to force its way in, through doors or crevices, on opposite sides of the house.  As the general winds are caused by the direct influence of the sun’s rays upon the atmosphere, that particular deviation of the current distinguished by the name of land and sea breezes is caused by the influence of his reflected rays, returned from the earth or sea on which they strike.  The surface of the earth is more suddenly heated by the rays of the sun than that of the sea, from its greater density and state of rest; consequently it reflects those rays sooner and with more power:  but, owing also to its density, the heat is more superficial than that imbibed by the sea, which becomes more intimately warmed by its transparency and by its motion, continually presenting a fresh surface to the sun.  I shall now endeavour to apply these principles.  By the